1. Field Of The Invention
This invention relates to attachments of a rotor to a shaft wherein the axial positioning of the rotor in relation to a housing is important. More particularly, the invention relates to attaching a vane type rotor to a motor shaft of a vacuum pump, air compressor or air motor.
2. Discussion Of The Prior Art
Prior methods of attaching a rotor to a shaft include pressing the rotor onto a shaft, adhesive bonding, pressing the rotor over an expanded metal ring located on a shaft groove, and securing the rotor to a shaft by using a set screw that tightens the rotor against a flat on the motor shaft. All of these methods have drawbacks which include the difficulty of setting an end clearance between the rotor and the motor housing, distortion of vane slots, rotor out of roundness when pressing over the motor shaft and inadequate bonding strength when using adhesives.
It is also known in the art to provide an adjustment for the clearance between an impeller and its housing wall by axially adjusting the position of the impeller shaft. This is disclosed in U.S. Pat. Nos. 2,434,979; 3,034,443; and 3,164,097. In U.S. Pat. Nos. 1,884,974; 4,080,094; 4,281,942; and 4,328,856, springs are utilized to provide an axial biasing force on a rotary shaft.
For sliding vane vacuum pumps, compressors, and air motors, to minimize leakage past the axial ends of the vanes and between the end of the rotor and the housing, it is desirable to provide a very small clearance between the rotor and the end wall of the motor housing. The attachment should be simple, economical, reliable and easy to assemble, while allowing accurate axial positioning of the rotor relative to the housing, so as to minimize leakage. The present invention addresses this need in the art.